Husqvarna 122C Workshop Manual

Also see for 122 LD X-series: Spare parts Operator's manual

406 Cylinder and pistonSmall score marks and a matt, grey surfaceon the piston’s inlet side caused by fine dustparticles.Foreign objectsEverything other than clean air and pure fuel that enters the engine’s inlet port cau-ses some type of abnormal wear or damage to the cylinder and piston.This type of increased wear shows on the piston’s inlet side starting at the loweredge of the piston skirt.The damage is caused by badly filtered air that passes through the carburettor andinto the engine.The guide pin for the piston ring has beenpushed up through the top of piston.Irregular grooves on the piston’s inlet sidecaused by a broken roller retainer.Deep, irregular grooves caused by a loosecirclip. Shown here on the piston’s inlet side.Piston ring guide pinvibrated looseA too high engine speed can cause theends of the piston ring to hammer againstthe guide pin when the piston ring movesin its groove. The intensive hammeringcan drive out the pin through the top of thepiston causing serious damage also to thecylinder.Damage caused bygudgeon pin circlipsA too high engine speed can causethe gudgeon pin circlips to vibrate. Thecirclips are drawn out of their grooves dueto the vibrations, which in turn reducesthe circlips’ tensioning power. The ringscan then become loose and damage thepiston.Bearing failureFailure of the crankshaft bearing or on theconnecting rod bearing is usually causedby a too high engine speed, resulting in thebearing being overloaded or overheating.This in turn can cause the bearing rollersor ball to glide instead of rotate, which cancause the roller or ball retainer to break.The broken debris can be trapped betweenthe piston and cylinder wall, damaging thepiston skirt.Debris can also pass up through thecylinder’s transfer channels and causedamage to the top and sides of the pistonas well as to the cylinder’s combustionchamber.